(1) Field of the Invention
The present invention relates to a netlike sheet wide by utilizable as a material for making, for example, light shielding nets, sheets for civil engineering applications, sheets for fruit containers, sheets for drying cereals, and various kinds of reinforcing materials, and to a method for producing a multilayer yarn for making such netlike sheet.
(2) Prior Art
It has been known that woven fabrics can be produced from multilayer yarns composed of stretched yarns of thermoplastic synthetic resins provided thereon with layers of thermoplastic synthetic resins which have a melting point lower than that of the thermoplastic synthetic resin used in making the stretched yarn. For instance, Japanese Utility Model Publication No. 53-49902 discloses a process in which a woven fabric is woven from multilayer yarns of this type and the outer thermoplastic synthetic resin layers are heated to a temperature higher than the melting point hereof so that the multilayer yarns disposed as warp and weft are adhered to each other in a thermocompression bonding manner to obtain woven sheets.
The warp and weft yarns used in such process are composed of multilayer yarns each of which comprises a stretched yarn disposed at the interior thereof and, therefore, the woven sheets produced therefrom are too low in stiffness for use as light shielding nets, sheets for civil engineering applications and various reinforcing materials. Moreover, the low strength creates problems concerning deforming of the woven fabrics during weaving of the yarns into fabrics and/or storing the same, which in turn results in low yield.
In order to eliminate the foregoing problems, it would seem effective to increase the thickness of the stretched yarns and low melting theremoplastic synthetic resin layers constituting the warp and weft yarns. However, such a method is not effective for imparting the desired stiffness to these yarns. This is because if thick stretched yarns should be prepared by the method, non-uniform multilayer yarns would be obtained.